Heater insulator



FIG. 1 is a perspective view of a heater insulator which embodies my design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a top view thereof; the bottom view being a mirror image thereof. 

The ornamental design for a heater insulator, as shown and described. 